Various biologic products are produced from biological materials obtained from human and non-human sources. These biologic products can be administered to humans as a medical treatment. Thus, it is desirable and, in fact, imperative that the biologic products be free from infectious components, for example, active viral agents.
A major source for such biologic products is human blood plasma. For example, such biologic products can include various fractions of protein materials separated from human plasma, such as albumin, antithrombin III, fibrinogen, factor VIII (anti-hemophilic factor [AHF]), and the prothrombin complex, i.e., factor IX, together with factors II, VII and X.
Inactivation of viral agents, e.g., hepatitis B virus and/or non-A, non-B hepatitis virus, can be accomplished by treating the plasma before the fractions are separated, or the fractions can be treated after separation.
Various treatments to inactivate infectious agents in separated fractions have been used in the past. Such treatments can, for example, include the use of solutions containing bleach, alkali, and/or acids. However, using such solutions is highly deleterious to the labile protein fractions and can destroy their biological activity and, thus, their usefulness.
Other treatments that have been used in the past are exposure of separate protein fractions to ultraviolet radiation or .beta.-propiolactone.
Treatments are also known which use heat to inactivate infectious agents contained in plasma and in protein fractions separated from such plasma. For example, aqueous solutions of Antithrombin III, Factor VIII (AHF), albumin, Plasma Protein Fraction (PPF), and Factor IX have been heated to temperatures from 60.degree. C. to 100.degree. C. to inactivate viral components. Also plasma has been subjected to heat.
Alternatively, various protein fractions have been heated in the dry state, for example, as a powder, to deactivate viral components.
Heating aqueous solutions of protein fractions, or heating the protein fraction in its dry state, can result in the material losing a greater portion of its biological activity than desired. Furthermore, heating such materials in the dry state may not provide heating that is as uniform as desired.
Thus, there is a need in the art for a process that is relatively simple and inexpensive, that provides even heating to the protein fraction being sterilized, and that does not substantially reduce the biological activity of the material being treated.